Renal cell carcinoma (RCC) takes 12,000 American lives each year. Existing systemic therapies are curative in fewer than 10% of patients, and targeted therapeutic approaches are needed. Loss of the von Hippel Lindau (VHL) tumor suppressor is an early event in the development of most clear cell RCC, and preliminary studies have indicated that a critical function of VHL is ubiquitin-mediated degradation of hypoxia inducible factor alpha (HIF-alpha). HIF-alpha stability and transactivation are regulated by hypoxia and redox signaling by two independent mechanisms that involve binding of VHL and the transcriptional co-activator CBP/p300. A novel kidney-specific, superoxide-producing NAD(P)H oxidase, Renox, was recently described and implicated in oxygen sensing for maintenance of oxygen homeostasis via secretion of erythropoeitin. This exclusive renal function is known to require HIF transcriptional activation. The hypothesis of this proposal is that Renox-mediated accumulation of reactive oxygen species (ROS) within the renal cell influences activation of HIF-( leading to malignant transformation in the absence of functional VHL. There are three major aims of this work. The first is to determine the effect of Renox and ROS upon HIF-alpha regulation and activity. A second aim is to determine the effect of redox signaling upon HIF-alpha post-translational modification. The final aim is to specifically inhibit Renox function to determine its effects on the tumorigenic phenotype of renal cell carcinoma. Although this work is of high relevance to renal carcinogenesis, its has broader implications in the areas of renal microenvironment, oxidative stress in disease states, and general renal physiology. The candidate is a urologist with expertise in the area of molecular genetics of kidney cancer. She recently completed a research fellowship in urologic oncology at the National Cancer Institute. The candidate seeks to establish a career as an independent physician-scientist in an academic setting where 75% of her time is devoted to the laboratory and 25% to teaching and.clinical work. This will be achieved by a comprehensive program to acquire both technical and intellectual skills under the guidance of two distinguished and outstanding mentors, Shuk Mei Ho and Gary Stein, and to draw upon the scientific strengths of a number of investigators within the UMass Medical School community. This will provide an excellent environment for completion of this project and a basis for transition to independent investigator.